Industry Background
Williams Fire and Hazard Control, Inc. (Williams) has been a leader in the design, development, and production of specialty firefighting equipment and methodology for use on large industrial tank fires. A study published in a report by SP Fire Technology in 2004, written by Henry Persson and Anders Lonnermark, stated:                Despite the lack of large-scale tank fire tests in the last 15 to 20 years, significant improvements have been made regarding tank fire fighting using mobile equipment. The pioneers in this development have been Williams Fire & Hazard Control Inc. (WFHC) drawing attention to the need for solving the logistics during a fire and to use relevant tactics. By using large capacity monitors, large diameter hose and foam concentrate stored in bulk containers, the logistics become manageable. The use of large-scale monitors has also made it possible to achieve sufficiently high application rates in order to compensate for foam losses due to wind and thermal updraft. Williams have also introduced the “Footprint” technology where all the foam streams are aimed towards one single landing zone on the fuel surface, resulting in a very high local application rate making the foam spread more rapidly and efficiently. One of the main factors in achieving an efficient extinguishment, according to Williams, is the use of a high quality foam, suited for tank fire protection and until recently, they were primarily using 3M AFFF/ATC. Due to 3M's withdrawal from the foam business a similar foam type is now used, manufactured by Ansul. “Thunderstorm ATC.” In 1983, Williams extinguished a 45.7 m (150 ft) diameter gasoline tank in Chalmette, La. (“Tenneco fire”), which at that time was the largest tank ever extinguished using mobile equipment. A new record was set in 2001 when an 82.4 m diameter (270 ft) gasoline tank was extinguished in Norco, La. (“Orion fire”). The concept for tank fire fighting used by Williams has been shown to be successful in many other fires [35] and the concept has also been successfully used by other companies, e.g. during the Sunoco fire in Canada 1996.”(Note: Thunderstorm™ foam concentrates are now developed and produced by Chemguard Inc.) Historical Development        
Historically, Williams has specialized in mobile equipment and methodology. “Fixed system” approaches to large tank fires, historically, have demonstrated limited success in the industry as well as high cost.
On the one hand, for “rim seal fires” (fire around the rim of a tank floating roof, around the roof seal,) traditional fixed system approaches place a large number of “foam chambers” or “foam pourers” around the perimeter of the storage tank, every 40 feet or every 80 feet depending upon whether the “foam dam” on the floating roof is 12″ or 24″ highs. These devices drop or “pour” highly aerated fire fighting foam down the tank wall into the tank “periphery,” or area between the tank wall and the “foam dam” on the floating roof, by force of gravity. The cost for such system is high.
On the other hand, for “full surface liquid tank fires” in 100 foot plus diameter tanks, proven fixed systems have not existed. That is, to the inventor's best knowledge, no fixed system has put out a fully engaged full surface liquid tank fire in a 100 foot plus diameter tank.